WASHINGTON -- The argument over whether spending $1.75 billion on seven additional F-22 jets makes good economic sense is coming to a head between Congress and the Obama administration.

Lawmakers from states that would benefit from manufacturing the jets want the money pumped into the aerospace and defense industries. Defense Secretary Robert Gates counters that the money would be better spent on ensuring that the military has the tools it needs to fight the unconventional wars taking place in Iraq and Afghanistan.

An amendment to strip the F-22 money from a $680 billion defense spending policy bill is scheduled for a vote in the Senate on Tuesday. President Barack Obama has threatened what would be the first veto of his presidency if the F-22 money remains in the bill presented for his signature.

"What I have not heard is substantive reason for adding more aircraft in terms of our strategic needs," Gates said Monday while reiterating his opposition to the purchase.

Senate Armed Services Committee Chairman Carl Levin, D-Mich., and the top Republican on the panel, Sen. John McCain of Arizona, sponsored the amendment to take out the F-22 money. But there's strong resistance, particularly from senators representing states where the plane and its parts are made.

According to Lockheed Martin Corp., the main contractor, 25,000 people are directly employed in building the plane, and another 70,000 have indirect links, particularly in Georgia, Texas and California. Sen. Chris Dodd, D-Conn., a supporter of the program, said there are 1,000 suppliers in 44 states.

Dodd, speaking on the Senate floor last week, questioned why Congress should approve $65 billion to prop up the automobile industry but can't spend $1.75 billion to support an important segment of the aerospace industry.

Supporters of the program also argued that it would undermine the nation's security to terminate the F-22 when China and Russia are both developing fighter jets that can compete with it.

The Senate took up the F-22 issue last week, but then put it aside to deal with two amendments having nothing to do with defense. On Thursday senators voted to adopt a major expansion to hate crimes law, and on Monday they turned to a proposal allowing people with concealed weapons permits in one state to carry their weapons into other states. A vote on the gun law was expected Wednesday.

Its sponsor, South Dakota Republican John Thune, said the permit holder must respect the concealed weapon laws of the state he is visiting, such as bans on firearms in certain locations. There would be no right to carry concealed firearms in the two states that do not allow the practice, Wisconsin and Illinois. The measure is backed by the National Rifle Association and other gun rights groups.

Sen. Frank Lautenberg, D-N.J., a gun control advocate, charged that it was a "reckless amendment that would force states from coast to coast to comply with the weakest concealed carry laws." For example, he said, a state that requires training for those seeking permits would have to allow people from states that don't require training to enter with hidden weapons.

The House last month approved its version of the defense bill with a $369 million down payment for 12 additional F-22 fighters. The House Appropriations Committee last week endorsed that spending in drawing up its Pentagon budget for next year. It also approved $534 million for an alternate engine for the F-35 Joint Strike Fighter, another program that Obama, backed by the Pentagon, says is unwarranted and would subject the entire bill to a veto.

The defense bill authorizes $550 billion for defense programs and $130 billion for military operations in Iraq, Afghanistan and other anti-terrorist operations.